This invention is directed toward a buoyant blood stop valve which stops blood flow as blood is exhausted. The valve may also be used for cutting off other types of liquid flow when the liquid approaches exhaustion from the reservoir.
During open-heart surgery, both the heart and lungs are bypassed with an extra-corporeal circuit which includes a pump and an oxygenator. In a hard-shell oxygenator, oxygen is bubbled through the blood, and the displaced carbon dioxide escapes from the blood. The oxygenated arterial blood is filtered and returned to the body. Air can be inadvertently introduced into the arterial line when the reservoir contents of the hardshell oxygenator is accidentaly emptied, such as when no more venous blood is being fed to the oxygenator, but the blood in the reservoir is being returned to the patient. The introduction of air into the arterial line can cause massive air embolism and usually death of the patient.
Thus, there is need for a valve to be positioned in the arterial line, which presents as little resistance to flow as is possible, which minimizes blood turbulence and trauma that may cause hemolysis and which closes automatically when massive air or other gas reaches the valve so that the valve shuts off before air passes into the arterial line beyond the blood stop valve. Such a valve should not have a tendency to inadvertently close during normal flow and should not require external manipulation or separate sensors or signals to actuate the valve. Such a valve should be pre-sterilizable and inexpensively producible.